An old bug of WP? You don't have permission to access /wp-admin/po

Another update : when I am editing another page then the error is not showing.

But for one page this error is being shown.

I dont know is it right to show my URLs or not ?

But I am giving this URL dont create problem during page update

But this page creating problem during update and showing forbidden error.

I am confused.

WordPress reads URL something like this when you work on editing already published posts

your-site.com/wp-admin/post.php?post=835&action=edit

and a new post

your-site.com/wp-admin/post-new.php

It seems you mess up with

/seoupdation/wp-admin/post.php

I found the problem zone. I have some PHP code in my article body of wordpress like the following `
<?php
include(ABSPATH. ‘../somefilepath.php’);
require_once(ABSPATH. ‘../another-file-path.php’);
?>
`

Have Exec-PHP plugin installed, but still this area creating problem.

I am sure of it.

@bottleneck :

When I am in edit mode URL of address bar is :
domain.com/wp-admin/post.php?post=42&action=edit

But when I am submitting the page : URL is
domain.com/wp-admin/post.php

then the error shows up-

I have just updated this page , no error shown but when I am adding some baic PHP code like
<?php echo "hello world";?>
it works fine, I think some problem in PHP path.

As I have guessed the whole problem lied in the PHP section. Extra space inserted or something. Now I have fixed all used the following type of code : All bugs lied in PHP code snippet placed into articles.